Hydraulically driven vehicle and cable reel motor control means



Aug- 7, 1951 c. P. BALDWIN Erm. 2,562,881

HYDRAULICALLY DRIVEN VEHICLE AND CABLE REEL MOTOR CONTROL MEANS OriginalFiled Feb. 15, 1941 11 Sheets-Sheet 1 In ven/fori: ldebald w Ha'rryHTI/andw 7a2. y

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Aug. 7, 1951 c P. BAL wlN ETAL HYDRAULICLLY DRI REEL MOTOR coN'rRoLMEANS original Filed Feb. 1s. 1941 N VEHICLE AND CABLE 11 Sheets-Sheet 515u/anion? Zyaka Zdwv'm, 17a fry/; Winde/fee- U8- 7 1951 c. P. BALDWINErm. 2,562,881

HYDRULICALLY DRIVEN VEHICLE AND CABLE n REEL MOTOR CONTROL MEANSOriginal Filed Feb. 13, 1941 1'1 sheets-sheet 4 0/ l 75 [a/anfora? fldealdwn l ZrryH /az MAM/Ma.

Aug- 7, 1951 c. P. BALDWIN ETAL 2,562,881

HYDRAULICALLY DRIVEN VEHICLE AND CABLE REEL MOTOR CONTROL MEANS OriginalFiled Feb. l5, 1941 11 Sheets-Sheet 5 /az 5556/a/ 95 9F y? W55 y /02 2//38 /37 /a 77 95 om;

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HYDRAULICALLY DRIVEN VEHICLE AND CABLE REEL MOTOR CONTROL MEANS OriginalFiled Feb. 13, 1941 l1 Sheets-Sheet 6 A118- 7, 1951 c BALDWIN ETAL2,562,881

HYDRAULICLLY DRIVEN VEHICLE AND CABLE REEL MOTOR CONTROL MEANS 11Sheets-Sheet 7 Original Filed Feb. 13. 1941 fnvenbm'r 12911761350lain/('11. Y W jyan'jylfandegce.

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All@ 7, 1951 C. P. BALDWIN ETAL 2,562,881

HYDRAULICALLY DRIVEN VEHICLE AND CABLE REEL MOTOR CONTROL MEANS OriginalFiled Feb. 15, 1941 ll Sheets-Sheet 8 Eiglg. 3g [ff/3 3/3/5 3W l Y (I 5a 3M 5 Allg- 7, 1951 c. P. BALDWIN ETAL 2,562,831

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Allg 7, 1951 c. P. BALDWIN ETAL HYDRAULICALLY DRIVEN VEHICLE AND CABLE yREEL MOTOR CONTROL 's Original Filed Feb. 13, 1941 11 Sheets-Sheet lOawy.

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Patented Aug. 7, 1951 HYDBAULICALLY DRIVEN VEHICLE AND CABLE REEL MOTORCONTROL MEANS Clyde P. Baldwin, Claremont, N. H., and Harry 1I.

Vanderzec, Racine, Wis., assignors to Joy Manufacturing Company, acorporation ot Pennsylvania Original application February 13, 1941,Serial No. 378,728. Divided and this application February 15, 1945,Serial No. 578,084

23 Claims.

This invention relates to mining apparatus, and more particularly toimprovements in coal mining apparatus of the universal type especiallydesigned for use in trackless coal mines, and capable of performing anumber of different functions with eillciency and economy.

An object of the present invention is to provide an improved coal miningapparatus especially designed for use in trackless coal mines, `whichmay be readily maneuvered and is capable of performing a, number ofdifferent functions with comparative ease. Another object is to providean improved coal mining apparatus mounted on and propelled and steeredby relatively large.

pneumatic-tired wheels whereby the uneven floor of a trackless coal minemay be readily traversed, without undue shock and distortion. A furtherobject is to provide a rubber-tired coal mining apparatus which is of a.relatively compact construction and having relatively great flexibilitypermitting ready maneuverability of the apparatus in confined spaces inunderground coal mines. Another object is to provide improved tractionwheel mountings and driving means for the traction wheels. Yet anotherobject is to provide an improved coal mining apparatus having animproved power operated steering mechanism whereby the apparatus may bereadily steered through the sharply curved and relatively restrictedpassages of a coal mine. A further object is to provide an improved coalmining apparatus having an improved cable reel, and improved driving andcontrolling means therefor. A still further object is to provide animproved coal mining apparatus having an improved hydraulic system whichembodies improved control valve means for controlling the flow of fluidunder pressure with respect to the various hydraulically operateddevices. Still another object is to provide an improved coal miningapparatus having novel combinations and arrangements of parts. Furtherobjects and advantages will become apparent as the description proceeds.

The improved mining apparatus. according to a preferred embodiment ofthe invention, may, for purposes of convenience, be mounted onrelatively large, pneumatic-tired wheels whereby the same may move aboutthe mine without the use of a trackway, and be provided with propellingand steering mechanism whereby the same may be propelled at any desiredspeed and may be readily maneuvered through the sharply curved andrelatively restricted passages of a coal mine. The invention. from thestandpoint of a number 2 of its aspects, may be of the universal typecapable of performing a. number of different functions with efficiencyand economy, in that kerfs may be cut in a coal seam at variouslocations. 'The kerf cutting mechanism of the apparatus selected for theillustrative embodiment of the invention may have relatively greatexibility whereby the same may be positioned to cut horizontal kerfs inthe coal face at either the floor or the roof level. or at any desiredintermediate level, and also to cut shearing kerfs in various planesperpendicular or inclined with respect to said horizontal kerfs, andalso to cut horizontal and vertical kerfs in the ribs at either side ofthe coal face. The apparatus may embody hydraulically operatedpropelling means for driving the front traction wheels at any speedbetween zero and a predetermined maximum; and hydraulically operatedsteering mechanism may be associated with the rear steering wheelswhereby the apparatus may be readily and easily steered. The apparatusmay also embody, to effect the various adjustments of the kerf cuttingmechanism, hydraulically operated adjusting means which may be readilycontrolled so that any desired speed of adjustment and movement may beobtained. All the different functions of the apparatus may be performedas the results of simple manipulations and adjustments, and theadjustments may be performed quickly and with a minimum of skill andlabor, due to the foolproof manner of control. The apparatus may moveover an uneven mine floor without undue strain or distortion, and by theprovision of hydraulically operated levelling and stabilizing mechanismthe apparatus may be readily levelled. for cutting, and tilting tendencyof the apparatus during certain kerf cutting operations may be oiset. Bythe provision of a novel hydraulic system embodying improved controlvalve means the flow of liquid under pressure with respect to thevarious hydraulically operated devices may be readily controlled, toobtain the most advantageous results. The arrangement of the apparatusis compact and the parts are designed to provide proper balance. Whilethe various features mentioned may all be included in a pre-- ferredembodiment of the invention, it will be apparent that the latter iscapable of wide variations in different embodiments, and, accordingly,reference to the appended claims should be had for a knowledge of thescope of the invention.

In the accompanying drawings, in which there is shown for purposes ofillustration one form which the invention may assume in practice,

Figs. 1 and 3, when taken together, constitute a plan view of theimproved mining apparatus, with a portion of the top cover broken awayto facilitate illustration.

Figs. 2 and 4, when taken together, constittue a side elevational viewof the mining apparatus shown inFigs. 1 and 3.

Fig. 5 is an enlarged vertical sectional view taken substantially online 5-5 of Fig. 1.

Fig. 6 is an enlarged vertical sectional view taken substantially online 6-6 of Fig. 1, with parts omitted.

Fig. 7 is a horizontal sectional view taken substantially on line 1-1 ofFig. 5.

Fig. 8 is a cross-section view taken substantially on line 8-8 of Fig.5.

Fig. 9 is a cross-sectional view taken substantially on line 9-9 of Fig.6.

Fig. 10 is a cross-sectional view taken substantially on line Ill-III ofFig.6.

Fig. 11 is an enlarged view in longitudinal vertical section takensubstantially on line II-II of Fig. 1.

Fig. 12 is a detail sectional view taken substantially on line I2-I 2 ofFig. 1l.

Fig. 13 is a horizontal sectional view showing details of the turntablemounting, turntable rotating means and the motor for rotating the cutterhead.

Fig. 14 is an enlarged cross-sectional view taken online I4-I4 of Fig.3.

Fig. 15 is a horizontal sectional View taken substantially on line I5-I5 of Fig. 14.

Fig. 16 is a detail vertical sectional view taken substantially on lineIG--IE of Fig. 14.

Fig. 1'1 is a vertical sectional view taken through one of the tractionwheel driving motors and its associated transmission mechanism.

' Fig. 18 is an enlarged vertical sectional view taken substantially online IS-Il c! Fig. 3. showing a portion of the driving means for thecable reel.

' Fig. 19 is a vertical sectional view taken substantially on line I9I9of Fig. 18 with parts shown in full, and a portion of the casing brokenthe control valve mechanism.

Fig. 22 is a vertical sectional view taken substantially on line 22-22of Fig. 21.

Fig. 23 is a vertical sectional view taken su stantially on line 23-23of Fig. 21.

Fig. 24 is a vertical sectional view taken sub-` stantially on line24-24 of Fig. 21.

Fig. 25 is a diagrammatic View illustrating the hydraulic systemembodying the control valve mechanism shown in Fig. 21.

Fig. 26 is a diagrammatic plan view illustrating the improved miningapparatus in a mine entry with the kerf cutting mechanism in horizontalcutting position. Fig. 27 is a diagrammatic side elevational viewshowing the mining apparatus in a mine entry with the ker! cutter inhorizontal top cutting position.

Fig. 28 is a diagrammatic view similar to Fig. 27, showing the kerfcutter inhorizontal bottom cutting position.

Fig. 29 is a diagrammatic side elevational view showing the -apparatusin position to insert a shearing kerf in one of the ribs.

In the illustrative embodiment of the invention there is shown a coalmining apparatus of the universal type especiallydesigned for use intrackless coal mines. It will be evident, however, that various featuresof the invention may be embodied in mining apparatus of various othertypes, and, if desired with respect to such features, the apparatus maybe mounted on track wheels to travel along a mine trackway, or may betractor-tread mounted.

The mining apparatus illustrated generally comprises a main frame orbody I mounted on iront traction wheels 2 and rear steering wheels 3.The main frame or body carries at its forward end adjustable kerfcutting mechanism, generally designated 4, including a kerf cutter 5.The front traction wheels have driving means, generally designated 6, 6,while associated with the rear steering wheels is power operatedsteering mechanism, generally designated 1. A motor 8 drives the kerfcutter, while a separate motor 9 drives the pumping means of thehydraulic system, and the latter embodies control valve mechanism,generally designated III. Levelling, or adjusting devices II, II areassociated with the mountings for the front traction wheels, while astabilizing device I2 is associated with the mounting for the rearsteering wheels. A cable reel mechanism, generally designated I3, isarranged at the rear end of the main frame or body.

Now referring to the kerf cutting mechanism 4, it will be noted thatcarried at the front end of the main frame or body I intermediate thefront traction wheels is a horizontal turntable I4 having a generallyannular horizontal frame I5 (Figs. 6 and 10) journaled in bearingsleeves supported by an annular bearing support portion I6 of themachine body. 'I'he turntable frame has, near its rear edge, anupstanding bracketl II which, as shown in Fig. 13, supports a horizontalpivot shaft I8, and an elongated arm structure or boom I9 has brackets20 at its rear end pivotally mounted on the projecting ends of the pivotshaft I8, in the manner shown. The arm structure or boom overlies theturntable and extends forwardly in advance of the forward end of themain frame or body; and the intermediate portion of the boom, consideredas a. whole, has a projection 2| (Figs. 5 and 6) providing spacedbearings on which is journaled the bearing portion 22 of a rotatablecutter carrying head 23, which constitutes the outer portion of theboom. It is accordingly evident that the cutter carrying head may rotateupon the longitudinal axis of the boom upon an axis perpendicular to a,line parallel to the boom pivot axis. The bearing portion 22 of the boomhas a yoke-shaped outer portion including side arms 24, 24 which supportalined pivot pins 25 on which brackets 26 integral with a cutter supportframe 21 are pivotally mounted, as shown in Fig. 8, thereby to enablethe cutter carrying head 23 to swing about an axis at right angles tothe axis of boom rotation. The cutter support 21 of the rotatable cuttercarrying head 23 has a cylindrical bearing support 28 which supportsbearing sleeves on which the circular bearing portion 29 of a cuttercarrying hanger frame 30 is pivotally mounted to swing upon an axis atright angles to a line parallel to and forward of rotation in line withthe axis of rotation of the cutter carrying head. As shown in Fig. 6,connected by a coupling 33 to the front end of the motor shaft 32 is analined shaft 34 journaled at its forward end in a bearing supported atthe front end of the bearing support 2l of the intermediate boomportion.

Various means may be employed to connect the shaft 34 with the cuttingdevices, to effect drive of the latter in the various positions thereof,but herein there is shown keyed to the front end of the shaft 34 anelement of a conventional universal joint 35 (Fig. 5) which is in turnconnected to a conventional universal joint 36, the latter having anelement keyed to a shaft 31 Journaled in bearings supported within theframe of the tiltable cutter carrying head 23. Keyed to and driven bythe shaft 31 is a bevel pinion 38 meshing with and driving a bevel gear39. As shown in Fig. 5, the bevel gear 39 has its hub 40 journaled bymeans of bearings supported by a drive shaft 4l, the latter in turnjournaled in bearings supported within the tiltable cutter carryinghead. The bevel gear hub 40 may be connected in various ways, and isherein shown as connected by interleaved clutch discs 42 and a sleeve 43keyed to the shaft 4I. These clutch discs are loaded by springs 44 setat a predetermined pressure, so that the clutch may slip automaticallyupon overload. Keyed t and driven by the shaft 4I is a chain sprocket 45which engages and drives an endless cutter chain 46 of the kerf cutter.The kerf cutter includes an elongated plane cutter bar 41 on the marginof which the cutter chain is guided for circulation, and S this cutterbar is carried by the swiveled hanger frame 30. It will thus be seenthat the cutter chain may be driven through the connections abovedescribed irrespective of the position of the cutter head about itsaxis, the tilted position of the cutter support, or the swiveledposition of the bar hanger frame.

For swinging the boom in a vertical direction about its pivot relativeto the turntable, there are provided, at the opposite sides of the boom,upright hydraulic cylinders 49 having lateral trunnions pivotallymounted at 50 in brackets 5| rigidly secured to the boom. As shown inFig. 10, these cylinders contain pistons 52 fixed to piston rods 53which extend downwardly through the packed lower cylinder heads 54 andare pivotally vconnected at 55 at their lower ends to brackets 56secured to the top of the turntable frame l5. The pivotal axes of thecylinders 49 and the axes of pivotal connection of the piston rods withthe turntable frame are parallel t0 the pivotal axis of the boom, sothat when the boom is swung the cylinders and piston rods swing abouttheir respective pivots.

The cutter support 21 may be swung about its pivot relative to therotatable boom portion 22 in various ways, and is herein shown asadapted to be so swung by a hydraulic cylinder 58 (see Fig. arranged atthe same side of the cutter support as the kerf cutter and pivotallymounted at 59 on projections 60 integral with the boom portion 22.Reciprocable in this cylinder is a piston 6I having its piston rod 62extending forwardly through the packed front cylinder head 63 andpivotally connected at 64 to projections 65 integral with the cuttercarrying head 23. The cylinder and piston rod pivot axes are parallelwith the pivotal axes of the cutter carrying head 23. The means forswinging the bar hanger frame on its bearing mounting relative to thecutter carrying head 23 to effect cutter bar swing comprises hydrauliccylinders 61 (Fig. 7) arranged at the opposite sides of the tiltcylinder 58 and suitably supported, these being herein shown aspivotally mounted at 68 on brackets 69 integral with the cutter carryinghead 23, and also on lower brackets 69 rigidly connected to the cuttercarrying head 23, and these cylinders contain reciprocable pistons 10having their piston rods 1l extending forwardly through the packed frontcylinder heads 12 and pivotally connected at 13 to projecting lugs 14integral with the hanger frame 30. The pivotal axes of the cylinders andpiston rods are parallel to the swivel axis of the hanger frame. It willthus be seen that when liquid under pressure is supplied to one end orthe other of the cylinders above described the associated parts may beswung about their respective pivotal axes, and when the liquid istrapped in these cylinders the parts are locked against pivotalmovement. The means for supplying liquid under pressure to thesecylinders will later be described.

The cutter head rotating means for rotating the cutter carrying head 23about the longitudinal axis of the boom may assume various suitableforms, and as herein shown comprises a conventional hydraulic motor 16mounted on the motor casing at the rear end of the boom. This motor isof the reversible type and has a spur pinion 11 fixed to its power shaftand meshing, as `shown in Fig. 13, with a spur gear 18 secured to ashaft 19 suitably journaled within the motor casing. Secured to theshaft 19 is a spur gear 80 meshing with a spur gear 8| keyed to alongitudinal shaft 82. This shaft extends longitudinally over the top ofthe motor casing, as shown in Figs. 6 and 10, and is suitably journalledin bearings supported by the boom. Fixed to the forward end of the shaft82, near the forward end of the motor, is a chain sprocket 83 whichengages and drives an endless chain 84 which in turn engages a chainsprocket 85 formed on the rotatable boom portion 22 which supports therotatable cutter head. It is accordingly evident that, depending on thedirection of motor rotation, the cutter head may be rotated in onedirection or the other about the longitudinal axis of the boom. Forlocking the cutter head against rotation there is provided areciprocable locking pin 86 guided in a bore 81 on the top of the boomand receivable in appropriately located locking apertures 88 formed on aflange 89 integral with the rotatable boom portion 22. A coil spring 90constantly urges the locking pin toward its foremost, locking position,and the pin is withdrawable from its locking aperture against the actionof the spring through a link 9| connected to a pivoted operating lever92 arranged at the top of the motor casing. This lever has graspingportions 93, 93 arranged at the opposite sides of the boom, so that thelocking pin may be operated from either side of the apparatus.

The rotating means for the turntable I5 as herein shown compriseshorizontal hydraulic cylinders 95 (Fig. 13) pivotally mounted at 96within brackets 91 secured to the sides of the body of the apparatus.Contained in these cylinders are reciprocable pistons 98 having theirpiston rods 99 extending forwardly through the packed front cylinderheads |00 and pivotally connected at their forward ends at lill toprojecting lugs |92 integral with the turntable frame I5 at the sides ofthe turntable. The pivots of the cylinders and piston rods are parallelto the axis of turntable means for supplying liquid under pressure tothe turntable rotating cylinders will be later described.

Now referring to the traction wheel driving means 6, 6, it willbe notedthat, in the embodiment of the invention illustrated, mounted at the-opposite sides of the main frame or body I, between the front and rearWheels, are hydraulic motors |05, |05. These motors are of thereversible type and each comprises intermeshing motor rotors |06, |01suitably journaled within the motorcasing. Since these motors and thetransmission means between the rotors and the traction wheels areidentical in design, a description of the drive for one traction wheelwill suilce for both. As shown in Fig. 17, the motor rotor |06 is keyedto a transmission shaft |08 suitably journaled within bearings supportedwithin a gear housing |09 secured, as by screws 0, to the machine body.Keyed to the shaft |08 is a high speed gear I|| meshing with a gear 2journaled on bearings supported by a longitudinally extending shaft ||3.The shaft |I3 is arranged in parallelism with the shaft |08 and islikewise journaled within bearings supported within the housing |09.Secured to the shaft |08 is also a slow speed gear I4 meshing with alarge gear ||5 arranged coaxial with the gear ||2 and likewise supportedin bearings supported by the shaft ||3. The gears ||2 and I|5 constitutethe high and low speed terminal gears respectively 0f the high and lowspeed transmissions, and are selectively connectible to the shaft I I3by means of disc clutches II6 and ||1. These clutches compriseinterleaved clutch discs secured to sleeves integral with the gears andto a sleeve I I8 keyed to the shaft II3. The clutch operating meanscomprises a shipper ring I I9 splined to the sleeve and having camsurfaces engageable with rollers I2| carried by pivoted links |22mounted on the sleeve II8. These rollers are engageable with camsurfaces |23 formed on sleeves |24 surrounding and slidably mounted onthe sleeve I8. Engaging anannular groove on the exterior of the shippermember ||9 is a shipper yoke |25 secured to a reciprocable member |26.Formed on the opposite ends of the member |26 are oppositely actingpistons |21, |21 contained in the bores of hydraulic cylinders |28. Itwill thus be seen that when liquid under pressure is supplied to one orthe other of the cylinders |28 the shipper member ||9 may be shifted inone direction or the. other to apply, through the cam and rollerdevices, one clutch or the other, and as a result the shaft I I3 may bedriven at relatively high or low speeds in the same direction. The meansfor supplying liquid under pressure to the cylinders |28 will later bedescribed. Secured to the forward end of the shaft ||3 is a spur gear|30 meshing with a spur gear |3I secured to a longitudinal shaft |32.The shaft |32 is connected, through a conventional universal joint |33,to a shaft |34 which has telescopic splined connection at |35 with ashaft |36. The shaft |36 is connected through a conventional universaljoint |31 to a shaft |38 suitably journaled within a gear housing |39.Fixed to and driven by the shaft |38 is a bevel gear |40 meshing with abevel gear |4| having its hub |42 keyed to a front axle |43 to which afront traction wheel is secured. The gear housing |39 is formed integralwith a swingforegoing it is evident 8 able traction wheel mounting |44pivoted at |45 on a bracket |46 integral with the body of the apparatus,and the telescopic splined connection between the shafts |34 and |36 andthe universal joints permit relative swinging movement between the wheelmounting and the main body without interrupting the wheel drvef To guidethe traction wheel mountings relative to the body of the apparatus, eachmounting |44 has on its side towards the body an arcuate guide element|44 which is adapted to move in the guides |44 secured to the body ofthe apparatus. From the that the front traction wheels may be driven bythe hydraulic motors |05 through the connections above described ateither a relatively high maneuvering speed or a relatively low speedappropriate for cutting.

Associated with the traction wheel mountings |44 are the levellingdevices II, above referred to. The levelling devices each comprise ahydraulic cylinder |48 (see Fig. 11) having its lower head |49 providedwith lateral trunnions pivotally mounted at |50 within a bracket |5|secured to a wheel mounting I 44. Contained in the cylinder |48 is apiston |52 having its piston rod |53 extending downwardly through thepacked lower cylinder head and pivotally connected at |54 to aprojection |55 integral with the machine body. Liquid under pressure maybe supplied to the cylinders |48, |48 either independently orconcurrently to effect swinging of the wheel mountings about theirpivots relative to the main frame I, thereby to enable levelling of themain frame when the apparatus is supported on an uneven mine floor. Whenthe liquid is trapped within these cylinders, the parts are locked inadjustedv position. The means for supplying liquid under pressure to thelevelling cylinders will be later\ described.

Associated with each of the driving means for the front traction wheelsis a band brake each comprising a brake drum |56 (Fig. l1) secured tothe shaft |32 and having a cooperating brake band |51. These brakes areprovided with operating means comprising exible shafts |58 (Fig. 4)guided by suitably located guide rolls and connected to operating levers|59, |59 conveniently arranged at the opposite sides of the apparatus.

Now referring to the mounting for the rear steering wheels, it will benoted that a transverse rear axle |60 is pivotally connected at |6|(Figs. 14, 15 and 16) to the bottom of the main frame I, and the axis ofpivotal connection lies in the central longitudinal vertical plane ofthe apparatus. Swiveled axles |62 are pivotally mounted on verticalpivotpins |63 carried at the opposite ends of the transverse axle |60.Different suitable means for swinging the axles |62 to effect steeringmight be used, but as shown herein. the swiveled axles have projectingarms |64 connected by adjustable cross rods |65 and |66 to ai lever |61-For effecting movement of the steering wheels a hydraulic cylinder |68is pivotally mounted at |69 on the transverse axle |60. This cylindercontains a reciprocable piston |10 having its piston rod lever |61.liquid under pressure is supplied to one end or the other of thecylinder |66 the steering wheels may be turned in one direction or theother about ,their pivotal mountings at the opposite ends of thetransverse axle |60 through the lever |61, cross rods |65, |66 and arms|64. By reason of the linkage arrangement shown, differential adjustmentof the wheels is effected whereby the |1I pivotally connected to the Itis accordingly evident that when The stabilizing device |2 associatedwith tne V rear wheel mounting comprises a vertical cylinder pivotallymounted at its upper end at |16 on a bracket |11 secured to one side ofthe machine body. Contained in this cylinder is a piston |18 having itspiston rod |19 extending downwardly through the packed lower cylinderhead |80 and pivotally connected at |90 at its lower end to projections|9| integral with the transverse axle |60 near one end of the latter asshown in Fig. 14. Liquid may be trapped in the stabilizing cylinder |15at the opposite sides of the piston to hold the body of the apparatusrigidly against tilting movement about its pivotal connection at |6|with the transverse axle |60, or the piston may be allowed to float, andby supplying liquid to one end or the other of the cylinder asubstantial redistribution of weight among the several wheels, ascompared with that when there is free turning at the pivot IGI, ispossible. In running around the mine it is evident that it will beadvantageous to have the rear axle |60 free to pivot with respect to itspivot |6|. When the cutter bar is going to be swung to one side it isdesirable, however, to have the axle locked, for this will x the axisabout which tilting would take place to a line connecting the points ofcontact with the bottom of the front and back Wheels at the side of themachine towards which the cutter bar is to be swung. With the axle |60free to iloat, the tilt line would extend approximately from the pointof contact of the front wheel with the mine bottom to a point in theaxis of the pivot shaft ISI.

Also, if the machine were to tend to lose traction because themomentarily more heavily loaded one of the driving wheels engaged aslippery spot, suitable admission of fluid to the piston |15 can be usedto impose more of the weight `of the machine on the wheel which canobtain traction.

As previously mentioned a cable reel mechanism I3 is arranged at therear end of the main frame This reeling mechanism comprises a cable reel|93 (Figs. 3 and 4) of relatively large diameter arranged in anextremely vertically compact manner within the vertical limits of themain frame and journaled to rotate about a vertical axis lying in thecentral longitudinal vertlcal plane of the apparatus. Wound on the reelis a conductor cable |94 by which motive power may be conducted to themotors 8 and 9, in a well known manner. The cable reel may be driven invarious Ways, but as herein shown is driven in a direction to wind inthe conductor cable by a hydraulic motor |95 having its housing |96secured to the side of the machine body. This motor comprisesintermeshing motor rotors |91 and |98 journaled within bearingssupported within the housing, as shown in Fig. 18. The rotor |91 iskeyed to a vertical shaft |99 (Fig. 18) likewise journaled withinbearings supported within the housing. Secured to this shaft is a spurgear 200 meshing with a spur gear 20| journaled on a vertical shaft 202herein arranged parallel with the shaft |99 and likewise journaledwithin bearings supported Within the housing. Slt-lined to the shaft 202is a clutch member 203 which is held in frictional engagement with afriction p`ate 204 secured to the gear 20| by a coil spring 205. Thisclutch is set at a predetermined load and is adapted automatically toslip upon overload. Keyed to the shaft 202 near its upper end is a chainsprocket 206 connected by an endless drive chain 201 to a chain sprocket208 secured to the reel. The means for controlling the supply of liquidunder pressure to the reel motor will be hereinafter more fullydescribed.

Referring to the hydraulic system, it will be observed that the motor 9has its power shaft 2|0 (Fig. 14) connected by a flexible coupling 2||to the drive shaftof pumping means 2|2. The pumping means may comprisetwo distinct pumping units, but, in this instance, comprises a dualpumping means having a pump 2|3 of low capacity discharge and a pump2|.4 of high capacity discharge. The control valve mechanism I0 ismounted in a horizontal position on the top of the machine body, asshown in Fig. 3, and beneath the valve mechanism is a liquid tank 2|5.As shown diagrammatically in Fig. 25, the pumps 2|3 and 2|4 have theirintakes respectively connected by conduits 2|6 and 2|1 to a liquidsupply conduit 2|8 leading to the tank, while the pump discharges arerespectively connected to conduits 2|9 and 220. The discharge conduit220 of the large capacity pump 2|4 leads to a conventional manuallycontrollable four-way valve device 22|, which has its valve-receivingbore connected by a conduit 222 to the tank. The large capacity pumpdischarge conduit has a relief valve 223 connected by a conduit 224 tothe conduit 222 leading to the tank, and this relief valve is set toopen automatically in the event the pressure in the system reaches apredetermined maximum, thereby to prevent overload of the system. Alsoleading from the valve-receiving bore of the fourway valve device areconduits 225 and 226, the latter being connected through branch conduits221 and 228 to the traction wheel driving motors |05. The conduit 225 isconnected through branch conduits 229 and 230 to the traction wheeldriving motors |05, the conduit 230 being connected to its motor throughthe by-pass valve for the cable reel driving motor, as will later bedescribed.

The control valve mechanism |0 comprises a valve box assembly'consistingof a number of valve box sections rigidly secured together by tie bolts232. Certain of the box sections are identical, and the differentsections are designated 233, 234 and 235 and all have valve-receivingbores 236. Contained in the bores of the different valve box sectionsare slide valves 231, 238, 239, 240, 24|, 242, 243, 244, 245, 246, 241and 248, and these valves control the flow of liquid under pressure fromthe discharge of the small capacity pump 2|3 to the various hydraulicmotors. Secured to the end valve box sections are intake and dischargesections 249 and 250. The small capacity pump has its discharge conduit2|9 connected to a supply passage 25| in the intake section 249, and thedischarge passage 252 in the discharge section 250 is connected by areturn conduit 253 back to the tank. Parallel longitudinal passages 254and 255 extend through all of the valve box sections and communicatewith the supply passage 25| but are blocked oil from the dischargepassage 252 by the wall of the discharge section 250, in the mannershown in Fig. 21. Also extending longltudinally through all of the valvebox sections midway between the parallel pasgroove 26| and end grooves262 and 263.

bores and with the discharge passage 252. A passage 259 controlled by arelief valve 260 connects the supply passage 25| with the dischargepassage 251, so in the event the pressure in the discharge of the lowcapacity pump becomes too high, the liquid will be automaticallyby-passed back to the tank. All of the slide valves with the exceptionof the valve 244, are of the spool type and have spools separated by acenrirral e valve 244 has a cylindric body 264 which has providedexternally thereon a series of longitudinal grooves 265, 266, 261 and268, the grooves 265 and 266 being centrally located in overlappingrelation while the grooves 261 and 268 are end grooves. The valves 231,238, 240, 242, 245, 246,

241 and 248 are held in their centrally located positions by oppositelyacting coiled springs 269, 269, so that when these valves are in theiroffcenter positions and are released the springs automatically centerthem. Spring detents 210 serve to hold the valves 239, 24|, 2.43 and 244in their different positions of adjustment. All of the valves have stemsprojecting outwardly through packed openings from the opposite ends ofthe valve box sections, and pivoted operating levers 21| areoperativelyV connected to the valve stems and arranged at the oppositesides of the valve box, thereby to enable'operation of the valves fromeither side ofthe apparatus. Cornmunicating with the valve-receivingbores 236 of each of the valve box sections are spaced passages 212 and213 which are connected through conduits to the various hydraulicmotors, as will later be explained. The end spools of al1 of the valves,with the exception of valve 244, are grooved or notched at 214 to enablesmoother and more gradual fluid flow past the valves, in a well knownmanner. The centering coiled springs 269 are arranged between detachableend caps 2,15 and collars 216 engaging shoulders provided by the endspools of the valves, and these collars are perforated or cut away toprovide free liquid flow past the same. As shown in Fig. 24, the valve244 has axial passages 211 and radial passages 218 and 219, and thesepassages connect the passages 212 and 213 with the discharge passages251 and 258 Vwhen the valve is in either of its end positions.Spring-loaded relief valves 280 and 28| automatically connect thepassages 212 and 213 with the discharge passages 251 and 258 whollyindependently of the slide valves, when the pressure in the hydraulicmotors becomes, for any reason, too high. The centrally located grooves265 and 266 on the valve 244 (Fig. 24) control the center by-pass 256while the end grooves 261 and 268 connect the passages 212 and 213 withthe discharge passages 251 and 258 in certain valve positions. In thevalve position shown in Fig. 24,

f the center by-pass 256 is open and the passages 212 and 213 areconnected to the discharge passages 251 and 258. In the other valvepositions shown (Figs. 22 and 23) for other valves the center by-pass256 is open and the passages 212 and 213 of those iigures are cut offfrom both the supply and discharge passages, and when these valves aremoved endwise in either direction certain ones of the passages 212, 213are connected to the supply while the others are connected to thedischarge, in an obvious manner.

The slide va ve 231 controls the steering mechanism for the steeringwheels, and the associated passages 212 and 213 communicating with thevalve-receiving bore are respectively connected by conduits 282 and 283to the opposite ends of the hydraulic steering cylinder |63. By Controlof this valve the steering wheels may be turned in one direction or theother by hydraulic pressure. The slide valve 236 controls the shippermechanism of the high and low speed transmission means of the tractionwheel driving means, and the associated passages 212 and 213 whichcommunicate with the valve-receiving bore in which valve 238 moves arerespectively connected by conduits 284 and 285 to the opposite ends ofthe clutch shipper cylinders |28. By control of this valve the high andlow speed clutches H6 and ||1 may be alternately applied and released byhydraulic pressure and held in applied position. The slide valve 239controls the traction wheel driving motors |05, and the associatedpassages 212 and 213 which communicate with its respectivevalve-receiving bore are respectively connected by conduits 286 and 281to the conduits 225 and 226 respectively, so that the motors |05 may beoperated in either of opposite directions to propel the apparatusforwardly or rearwardly by the liquid delivered by the low capacity pump2|3. The slide valve 240 controls the vertical swinging of the cuttersupporting boom I9, and the associated passages 212 andv213 whichcommunicate with the valve-receiving bore are respectively connected byconduits 288 and 289 to the opposite ends of the cylinders 49'. By thecontrol of this valve the cylinders 49 may effect raising and loweringof the boom by hydraulic pressure and holding of the boom in .adjustedposition. The slide valve 24| controls the rotation of the turntable,and the associated passages 212 and 213 which communicate with thevalve-receiving bore are respectively connected to conduits 298 and 29|each of which has branch conduits leading to the opposite ends ofdifferent cylinders 9'5. By the control of this valve the turntable maybe rotated by hydraulic pressure in either of opposite directions andlocked in its adjusted position to swing the cutter supporting boomlaterally in either direction and to hold the boom in its laterallyadjusted position. The slide valve 242 controls the rotation of thecutter carrying head 23, and the associated passages 212 and 213 whichcommunicate with the valvereceiving bore are respectively connected byconduits 292 and 293 to the head'rotating motor 16. Under the control ofthis valve the head rotating motor may be operated in either of oppositedirections to effect 'cutter head rotation in either of oppositedirections and to lock the head in its adjusted position. The slidevalve 243 controls the swinging of the kerf cutter about its pivot, andthe associated passages 212 and 213 which communicate with thevalve-receiving bore are respectively connected to conduits 294 and 295each of which has branched conduits leading to the opposite ends ofdifferent cylinders 61. Under the control of this valve the kerf cuttermay be swung in either of opposite directions about its pivot and lockedin `its adjusted position. The slide valve 244 controls the stabilizingdevice I2 associated with the rear wheel mounting, and the associatedpassages 212 and 213 which communicate with the valve-receiving bore arerespectivelyconnected through conduits 296 and 291 to the opposite endsof the stabilizer cylinder |15. Under the control of this valve, liquidunder pressure may be supplied to either end of the cylinder, dischargedfrom either or both ends of the cylinder, or trapped in both ends of thecylinder, for a purpose elsewhere more fully described. This valve maybe slid axially into ve different controlling positions, and in theposition shown in Fig. 24, the center by-pass 256 is opened and the endsof the cylinder are connected to the tank, so that the stabilizercylinder may float freely relative to the piston, but the valve may bepositioned to supply liquid under pressure to either end of the cylinderto move the cylinder either up or down, or to trap the liquid in thecylinder ends to lock the cylinder and piston against relative movement.The slide valve 245 controls the tilting of the cutter carrying head 21,and the associated passages 212 and 213 which communicate with thevalvereceiving bore are respectively connected through conduits 298 and299 to the opposite ends of the support tilting cylinder 58. Under thecontrol of this valve the cutter carrying head may be swung by hydraulicpressure to tilt the kerf cutter and to hold the kerf cutter in itsadjusted position. The slide valve 246 controls one of the levellingdevices II, and the associated passages 212 and 213 which communicatewith the valvereceiving bore are respectively connected by conduits 300and 30| to the opposite ends of one of the cylinders |48. The slidevalve 241 controls the other levelling device II, and the associatedpassages 212 and 213 which communicate with the valve-receiving bore arerespectively connected by conduits 302 and 303 to the opposite ends ofthe other cylinder |48. Under the control of the valves 246 and 241 thetraction wheel mountings may be swung by hydraulic pressure and lockedin adjusted position. The slide valve 248 controls the cable reel, andthe associated passages 212 and 213 which communicate with thevalve-receiving bore are respectively connected through conduits 305 and304 to an automatic by-pass valve device 308, and through this device tothe reel driving motor |95.

The automatic valve device 306, as shown in Figs. 18, 19 and 20,comprises a valve box 301 integral with the lower head of the reeldriving motor, and this valve box has a bore 308 in which isreciprocably mounted a slide valve 309. This valve is of the spool typehaving end spools 3I0 and 3| I separated by an annular groove 3I2. Thevalve body has an axial passage 3|3 plugged at its ends andcommunicating with the radial passages 3| 4 and 3 I 5 opening throughthe valve spool peripheries. A series of annular grooves 3|6, 3|1, 3I8and 3I9 are formed in the walls of the valve containing bore and the endgrooves 3I6 and 3I9 respectively communicate with the supply and exhaustpassages 320 and 32| of the motor. The valve box has chambers 3'22 and323 respectively communicable with the grooves 3| 1 and 3|9 throughpassages 324 and 325 controlled by spring-pressed check valves 326 and321. These check valves permit flow from the grooves to the chambers butprevent reverse flow. The end plates of the valve box have annulargrooves 323 and 329 which respectively communicate directly with theends of the valve containing bore 308 and are connected by passages 330and 33| respectively to the chambers 322 and 323'. When the reel drivingmotor is operating to drive the cable reel in cable winding directionduring drive of the traction wheels in the reverse direction, theautomatic valve is in the position shown in Fig. 19 and liquid underpressure coming from the conduits 281 and 228 and through one of thetramming motors and then through the conduit 333 may flow from theconduit 304 to the chamber 322 and through passage 330, groove 328, bore308 and groove 3I6 to the motor intake passage 320. 'I'he motor exhausttakes place through passage 32|, groove 3|9, passage 325, past the 14check valve 321 to the chamber 323 and thence to the conduit 308 andthrough conduits 230, 228, 288. past the valve 239, through the valvebox and by way of conduit 203 back to the tank. During driving oi thetraction wheels in the forward dlrection the cable reel is not drivenand the cable may be freely payed out. To prevent an excessive pressurebuilding up within the reel driving motor at that time, the automaticvalve device acts automatically to by-pass the liquid, as will now bedescribed. During forward drive of the traction wheels, liquid underpressure coming from the conduit 230 ows through a short portion of theconduit 305 to the chamber 323, and since the check valve 321 is closedliquid ilows through passage 33| and groove 329 to the valve containingbore at the right-hand end of the valve, as viewed in Fig. 19 and shiftsthe valve to the position shown in Fig. 20. The valve will remain inthis position because the iiuid which may pass through groove 330 willbe under a lower pressure, and the end of the valve will moreover beprobably at least partially sealed by surface contact with the left endof its chest. Fluid will, in this position of valve 309, pass throughpassage 332, to the bore 308 and between the end spools of the valve309, and then through groove 3I1 and passage 324, past the check valve326. through chamber 322, and via conduits 304 and 333 to the trammingmotor. After leaving the tramming motor the fluid will return by way ofconduits 228, 281, the main valve box and conduit 253 to the tank. I'hereel driving motor supply and exhaust passages 320 and 32| are,

' when the valve 309 is in the position of Fig. 20,

connected together by the by-pass passages 3|4, 3I3, and 3I5 in thevalve, so that the motor may rotate freely. It will thus be seen thatthe reel driving motor may be automatically by-passed during forwarddriving of the traction wheels. Conduits 334 and 335 connect thetraction wheel driving motors |05 to the return conduit 253', so thatany leakage past these motors will be returned to the tank. The reeldriving motor has a similar leak conduit 336 connected to the returnconduit 253. Arranged in the conduits 221 and 228 are manually operatedglobe valves 331 and 338 whereby the flow of liquid through theseconduits may be regulated. For instance, when one of the tractionwheels, for any reason, loses its traction by slippage, the increasedspeed of its driving motor would cause the liquid pressure to drop inthe motor supply conduit, and unless flow to the rapidly operatingdriving motor is restricted or cut oil', the driving motor for the othertraction wheel would stop. The conduits 225 and 226 are respectivelyconnected by conduits 339 and 340 to the supply conduit 2I8, and theseconduits 339 and 340 are provided with automatic check valves 34| and342 respectively which permit flow of liquid from thesupply conduit 2|8to the conduits 225 and 226 but automatically prevent reverse ilow.These automatic check valves serve to permit ilow of liquid to thetraction wheel driving motors |05 in the event the normal supply ofliquid in the hydraulic system should fail, for any reason, when theapparatus is moving down a steep incline. 'Ihe driving motors at suchtime operate as pumps which serve as brakes. If the automatic checkvalves were not provided, the driving motors would soon fail to act asbrakes. since the liquid would be pumped out, and in this constructionthe conduits 339 and 340 serve to replenish the liquid supply. Under thecontrol of the four-way valve device 22|, the discharge from drivingmotors.

l the high capacity pump 2 I4 may be connected t0 the wheel drivingmotors |05 through the conduits 225 and 226, and at times the dischargesfrom both pumps may be conducted to the wheel It is accordingly evidentthat the traction wheels may be driven at three different speeds bycontrolling'the ow of liquid from the pumps to the motors, and thesespeeds may be changed by the high and low speed transmissions. Also, byregulating the ilow of liquid to the motors by the control valves, thewheel driving speeds may be varied as desired. Thereby the apparatus maybe propelled through a wide range of low cutting speeds and through awide range of maneuvering and travelling speeds. It will be understoodthat the reel may be driven in a winding direction, when the apparatusis stationary, by suitably positioning the valve 248 to supply liquidfrom the valve box through the conduit 304 and permitting exhaust fluidfrom the reel driving motor to return through conduit 305.

. If the valve 248 is reversed, the cable may be freely pulled oi thedrum.

The general mode of operation of the improved mining apparatus is asfollows. The apparatus may be propelled about the mine at a relativelyhigh travelling speed by the motors |05 driving the front tractionwheels, and, at that time, the discharge of liquid under pressure fromboth pumps 2|3 and 2 I4 may be delivered to the motors. Motive power maybe supplied to the apparatus through the conductor cable from the usualtrolley power line in the mine entry. The operator may ride at eitherside of the apparatus on either of the platforms 343 provided for thispurpose and so located as to enable convenient access to the controllevers of the control valve mechanism I0, and the travelling speed andthe turning of the steering wheels may be controlled as desired by theoperator. Also the convenient location of the brake levers enables theoperator to brake the traction wheels at will so that in the case of anemergency, movement of the apparatus may be controlled, as for instance,when the apparatus is moving along a steep gradient. When it is desiredto turn the apparatus into a side passage or room and to leave the mineentry, the conductor cable is attached to the trolley line, and as theapparatus moves into the side passage or room the cable reel mechanismfreely pays out the conductor cable, the cable reel revolving freely atthat time with the liquid in the motor by-passing through the automaticbypass device 306. As the apparatus is propelled into the side passageor room from the mine entry, the large capacity pump 2| 4 may bedisconnected from the wheel driving motors by the four-way valve device22|, and at that time the motors may be actuated by liquid underpressure supplied thereto from the small capacity pump under the controlof the valve 239 of the valve mechanism I0. The discharge from the largecapacity pump is at that time conducted back to the tank by way of theconnection 222 through the four-way valve device. It will be noted,however, that if desired the discharge from the large capacity pump mayeither supplant or supplement the low capacity pump discharge to obtainthe desired wheel driving speed. When the apparatus is propelledrearwardly in the side passage or room towards the mine entry, the cablereel motor operatesto drive the cable reel 'in winding direction sothat, as the apparatus moves rearwardly, the cable is automaticallywound up under the control of the valve mecha- 16 nism I0. In the eventthat one of the traction wheels slips and the pressure in the dischargeof the low capacity pump suddenly drops, due to therapid rate ofoperation of the wheel driving motor at that time, the operatorv mayclose the proper one of the globe valves 331 and 330 to restrict or cutoff entirely liquid flow to that motor which drives the slipping wheel.By the provision of the globe valves the operator may prevent stallingof the apparatus, due to lack of traction of either one of the tractionwheels. When the apparatus is moving along a steep gradient and for anyreason the pressure in the hydraulic system fails, the wheel drivingmotors may serve as brakes to retard the traction wheels, and at thattime the flow of liquid to the motor is automatically replenishedthrough the check valve controlled conduits 339 and 341i.

Now referring to the mode of operation of the apparatus during the kerfcutting operation, it will be observed that when it is desired *J inserta horizontal cut in the coal seam, the apparatus is moved up to thecoalk face into the position shown in dotted lines in Fig. 26. Theturntable rotating cylinders are then operated to swing the cuttersupporting boom laterally and at that time the cutter swinging cylindersare operated to swing the cutter about its pivot relative to the boom.When the parts occupy the dotted line position indicated at A in Fig.26, the boom tilt cylinders 49 and the cutter tilt cylinder 58 may beconcurrently operated to locate the kerf cutter at the desired cuttinglevel. Fig. 27 shows the kerf cutter in horizontal cutting position atthe roof level, while Fig. 28 shows the kerf cutter in horizontalcutting position at the floor level, and any desired intermediatecutting level may be obtained by proper adjustment of the kerf cutter.When the kerf cutter is in the position indicated at A in Fig. 26 andliquid under pressure is supplied to the wheel driving motors |05 underthe control of the valve 239 of the control valve mechanism, thetraction wheels are driven to move the apparatus forwardly toward thecoal face at a low cutting speed to sump the kerf cutter in to the coal.As the apparatus moves 4forwardly, the cable reel freely pays out theconductor cable. When the kerf cutter is sumped into the coal, asindicated in dotted lines at B in Fig. 26, the liquid is trapped in thewheel `driving motors to hold the wheels stationary. The cutter swingingcylinders 61 are than operated to swing the kerf cutter about its pivotfrom the position indicated at B in Fig. 26 to the position indicated atC, to bring the cutter into alinement with the boom. Liquid underpressure is then again supplied to the turntable rotating cylinders andthe boom is swung horizontally to move the kerf cutter across the coalface from the position indicated at C to the position indicated at D,and thereafter the cutter swinging cylinders are operated to swing thecutter about its pivot from the position indicated at D to the positionindicated at E. The wheel driving motors are then reversed and theapparatus is propelled in a rearward direction to move the cutter fromthe position indicated at E to the position indicated at F, thereby towithdraw the cutter from the coal. As the apparatus moves rearwardly,the cable reel motor operates to drive the reel in a direction to windin the conductor cable. In Fig. 29 the apparatus is shown making anangled shear cut in a rib and during this shearing operation theapparatus is steered by the steering wheels so that it moves in anarcuate path while at the same time motion of the turntable, boom andcutter support is properly controlled to cause the sumplng of the cutterinto the rib, near the roof level. The boom swinging cylinders 49 maythen be operated to swing the boom downwardly to move the kerf cutterdownwardly in an arcuate path to make a shearing cut. Thereafter theapparatus is propelled rearwardly in the same arcuate path tf withdrawthe kerf cutter from the rib.

During the kerf cutting operations above described, the levellingcylinders of the levelling devices Il may be operated to swing thepivoted mountings for the front traction wheels. thereby to level up themain body of the apparatus when the mine floor is uneven, and theselevelling cylinders kmay also be employed to enable the kerf cutter toaccommodate itself to a rolling bottom or pitching seam, in a mannerobvious to those skilled in the art. When the cutter supporting boom I9is in a laterally located position at either side of the apparatus, thestabilizer cylinder will be operated to prevent pivoting about a lineextending from the front wheel nearer the face to the pivot ISI. Thestabilizer cylinder thus serves to hold the body of the apparatus rigidduring the cutting operation by locking the transverse rear axle and theapparatus body against relative tilting movement. It will be noted thatwhen the machine is standing on all four wheels there is a certain loadon the wheels on each side of the machine, part on the front wheel andpart on the rear wheel at either side. Now if all the load at the rearend of the machine be concentrated on one of the rear Wheels by forcingthe establishment of such an angular relation between the rear axle andthe rear end of the main body of the machine that only one rear wheelcontacts the mine floor, it will be evident that the front wheel at thesame side of the machine as the lifted rear wheel must support all theweight of that side of the machine and there is thus a reallocation ofweight among the wheels, the weight supported by the rear wheel whichstill contacts the mine bottom being substantially doubled, and theweight on the front wheel on the other side of the machine beingsubstantially increased. It will further be noted that the provision ofa pivoted rear axle with means for locking it in a fix-ed relation tothe machine body provides a very desirable arrangement. If the rear axlebe freely pivotable relative to the body the machine can be moved overan uneven bottom with very much less strain and roughness of movement.If, however, the boom be swung to the side with the rear axle thusfreely pivotally connected to the machine body, tilting about anobliquely disposed axis extending from the oorengaging part of the treadof one front Wheel to the rear axle pivot may be induced, 4but if thestabilizer be caused to hold the rear axle rigidly with respect to themachine body in such a position that the rear axle is parallel to theaxes of rotation of the front wheels, then the occurrence of tiltingwill be much harder to produce because the axis about which tiltingwould then occur would be a line at the side of the machine at bothfront and back-substantially a line connecting the contacts with thebottom of the front and rear wheels at the side of the machine towardsor beyond which the boom has been swung. Thus one improved wheelmountingfor the frame provides two very useful functions. As above pointed out,if wheel slippage occurs, the proper globe valve 331, 338 may beadjusted to prevent stalling.

As a result of this invention it will be noted that an improved coalmining apparatus is provided especially designed for use in tracklesscoal mines. It will further be evident that by mounting the miningapparatus on relatively large pneumatic-tired wheels the apparatus mayreadily move over the mine floor without the use of a mine trackway.Also, it will be noted that an improved mining apparatus is providedcapable of performing a number of different functions with eilciency andeconomy, it being possible to adjust the kerf cutter to cut horizontalkerfs either at the floor or roof levels or any desired intermediatelevel, or to cut shearing kerfs perpendicular or inclined to thehorizontal kerfs, and also to cut horizontal and vertical kerfs ineither rib. Further, by the provision of the improved hydraulicoperating and controlling means for the various devices of theapparatus, extreme ilexibility in operation is obtained. Also, by theprovision of the hydraulically operated levelling devices the apparatusmay operate on an uneven floor and the kerf cutter can accommodateitself to a rolling bottom or pitchingseam, and by associating therewiththe hydraulically operated stabilizer device, the possibility of tippingof the apparatus during the kerf cutting operation is substa-ntiallyreduced. These and other uses and advantages of the improved miningapparatus will be clearly apparent to those skilled in the art.

This application is a division of our application Serial No. 378,728,filed February 13, 1941, and now abandoned.

That portion of the invention hereinabove described, which relates to aland vehicle running gear with a rocking axle or, as it is referred toabove, to the stabilizing feature of the invention, constitutes thesubject matter of an application led by us February 21, 1949, Serial No.77,554.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What we claim as new and desire to secure by Letters Patent is:

1. In an apparatus of the character described. the combinationcomprising a portable base, a pump on said base having an intake and adischarge, driving means for said pump, a conductor for conductingoperating medium to said driving means, a reel for said conductor, ahydraulic driving motor for said reel having supply and exhaustconnections, propelling means for said base including a reversiblehydraulic propulsion motor, a sump, a connection from said sump to theintake of said pump, and means for selectively conducting the entirequantity of operating uid for said propulsion motor from the dischargeof said pump in series through said motors and back to the sump or forconducting the operating fluid for said propulsion motor from the pumpdischarge through said propulsion motor only in a direction to effectdrive thereof in an opposite direction, and back to the sump, whileinterconnecting the supply and exhaust connections of said reel drivingmotor, said last mentioned means including valve means controlling bothsaid supply and said exhaust connections and movable to interconnectthem with each other.

2. In an apparatus of the character described.

